A Straight or a Twisted Shofar? Staff at the Bar-Ilan University's Parashat Hashavua Study Center discusses what kind of ram's horn to use as a shofar. http://www.biu.ac.il/JH/Parasha/eng/rosh/fis.html
OU Presents Rosh HaShana About the holiday, as well as advanced articles. Also includes a collection of audio links. http://www.ou.org/chagim/roshhashannah/
Rosh HaShanah with Torah.org Project Genesis has educational resources, observances, and recipes. http://roshhashanah.torah.org/
The Virtual Beit Midrash A series of advanced lectures on Rosh HaShana, both philosophical and halachic. A resource for the serious student. http://www.vbm-torah.org/rosh.htm